Melaleuca alternifolia (tea tree)
Tea tree oil is an essential oil distilled from the leaves of the Australian tea tree. Most essential oils have some ingredients that can be used as pesticides. In recent years, doctors and scientists have become very interested in the possibility of using essential oils to treat lice. In the past, Western practitioners have relied on prescribing drug remedies for lice. But most lice in the United States have evolved to become resistant to conventional drug treatments. Many American doctors say that malathion is the only drug left that still effectively treats head lice in U.S. schoolchildren – most lice are resistant to other treatments.
Meanwhile, a 2006 Welsh study found that four out of five lice in Great Britain are resistant to all drug treatments, including malathion, so it is likely that malathion will not be effective in the U.S. much longer either. Consequently, scientists have begun doing studies to find out whether essential oils can be used effectively as insecticides. Tea tree oil, in particular, has attracted a lot of interest, and has been studied for use to prevent both head and body lice. The U.S. National Institutes of Health reports that early studies show that tea tree oil may be effective as a treatment for lice, but that larger studies are needed before it can be recommended.
Although tea tree oil may be effective for killing live lice, it is also necessary to remove any remaining nits (lice eggs) from hair, clothing, and bedding. Otherwise, the nits may hatch and the problem will recur.
Using Tea Tree Oil to Get Rid of Lice
Method for Head Lice
- Dilute oil with another oil, such as olive oil. Tea tree oil should comprise no more than 10 percent of your final oil mixture.
- Apply the diluted oil liberally to the hair and scalp.
- Cover the entire head with a shower cap or plastic wrap.
- Wrap a towel around the head.
- Leave on for about an hour, and then shampoo as usual.
- After shampooing, comb wet hair carefully with a fine-toothed comb or a lice comb, to remove nits (lice eggs). Do one ordinary comb-through or brush-through first to remove tangles. Then divide the hair into small sections, parting the hair so that you can see down to the root as you comb. You cannot do this for your own hair – someone other than the person being treated for lice must do the combing. This is a very important step—if you do not do a good job of removing nits, it may do little good to kill live lice with tea tree oil—any remaining eggs might still hatch and then you will have to start all over. This step takes a long time and is tedious, and boring for small children, but there is no way to treat head lice effectively without it.
- Wash clothing (especially headgear) and bedding, being sure to dry on a hot setting in the dryer for at least 20 minutes.
- Wash personal items that are used on the head, such as combs and brushes, barettes, hair fasteners, etc.
- Seal nonwashable items in plastic bags for a week, or, if possible (for stuffed animals, for example), dry nonwashable items in a hot dryer for 20 minutes.
- Repeat as needed until all signs of lice are gone.
Method for Body Lice
- Dilute tea tree oil with another oil, such as olive oil. Tea tree oil should comprise no more than 10 percent of your final oil mixture.
- Apply the diluted oil liberally to the skin.
- Leave on for at least an hour.
- Wash clothing and bedding, being sure to dry on a hot setting in the dryer for at least 20 minutes.
- Repeat as needed until all signs of lice are gone.
Why It Works
Tea tree oil, like most essential oils, contains compounds known as monoterpenoids, which have been found to kill lice in laboratory studies. Monoterpenoids disrupt the nervous systems of insects. Of all the monoterpenoids, the one that has been found to be the most effective at killing lice is terpinen-4-ol. Tea tree oil is made up of 30 percent terpinen-4-ol.
If you use a carrier oil, such as olive oil, to dilute the tea tree oil before treating for head lice, the carrier oil can also smother the lice, preventing them from getting any oxygen.
Before you begin any system of treatment for lice, be sure of your diagnosis. Head lice, in particular, are often misdiagnosed. Ordinary dandruff is frequently mistaken by parents for nits, or lice eggs. One way to tell the difference is to notice whether they fall out of the hair easily, or stick to the hair shaft. Nits will stick to the hair and are difficult to remove.
Topically, tea tree oil is considered generally safe. It does cause an allergic reaction, or contact dermatitis, in some people. One way to minimize the risk of contact dermatitis may be to dilute tea tree oil with a carrier oil, such as olive oil. You may also want to test for an allergic reaction by testing the oil on a small patch of skin before applying it to the entire scalp, which can be fairly sensitive. Most studies of the effectiveness of tea tree oil against lice have used very dilute concentrations of tea tree oil, such as 10 percent tea tree oil or one percent tea tree oil. When applying tea tree oil to the head, be careful to keep it out of the ears, as it has reduced the hearing of animals in animal studies (it hasn’t yet been applied inside the ears in human studies).
No one is likely to take tea tree oil internally for lice, but it is still worth noting that tea tree oil should never be taken internally, as it can be toxic even in very small doses, and can cause diarrhea, vomiting, sleepiness, confusion, impaired coordination, and even coma. Some people have an allergic reaction to tea tree oil applied topically, and others experience redness and irritation after using tea tree oil. According to one study, tea tree oil might be an endocrine system disrupter. Scientists are not sure about this, and the evidence is still scanty, but while the issue is being studied, tea tree oil should be avoided by people with hormone-sensitive cancers, and by pregnant or nursing mothers.